Grub and Software RAID1

Need a bit of help here. I have an active virtual mail server setup using software raid1 (ubuntu 6.06). I want to replace one of the hard drives so I can use it to build a duplicate system but I am worried about GRUB not working. When I initially set up the system I did not set up a separate /boot partition.

md0 = sda1+sdb1 and is 10 GB mounted at /
md1 = sda2+sdb2 and is 3GB set up as swap
When I first set this up I did not know I did not need to mirror swap -and not sure how to remove md1
md2 = sda3+sdb3 and is 30GB mounted at /home
md3 = sda4+sdb4 and is 31.15 GB mounted at /var